Analogue video are video signals wherein the image information is stored by analogue modulation on an electrical signal. There are many established color analogue video formats. Such color analogue video system specifies the video image in terms of the luminance or luma (Y) and chrominance or chroma (C) of the image. An analogue video decoder can receive in a single channel or signal a color analogue encoder video signal for example from a composite video input or from a television broadcast encoded analogue signal. The luma and chroma components of the analogue video signal can then be separated in such a way that they can then be output to a screen or display.
Analogue video is used in both consumer and professional applications and is found in many terrestrial television broadcast systems. For example, composite video, a format of analogue television picture (picture only) signals contain all the required video information including color in a single signal. Composite video is sometimes known as CVBS (composite video baseband signal). Composite video signals can be found, for example, in many standard formats such as NTSC (National Television System Committee), PAL (Phase Alternating Line), and SECAM (Sequential Color with Memory) as well as the various sub-standards of these standards such as PAL-M, PAL-N, NTSC443, PAL-60. The composite signal is a composite of three source signals Y (luma), U and V (representing hue and saturation or chrominance). The typical analogue video decoder receives such a composite video signal and separates these into the three source signals. However in order to apply correct color decoding techniques to separate the luma and chroma to produce the correct image on the final output screens, it is important to detect the correct mode or standard applied.
For PAL video decoding, in order to improve the luma/chroma separation, additional processing of the CVBS signals can be carried out. For example a process of 2D (spatial filtering) decoding and 3D (temporal, the inter frame or field comb filtering) decoding can be performed to attempt to improve the image quality. Performing field combing based only on motion detection can generate field motion artifacts due to field motion in phase subcarriers taps being spatially displaced.